The first aspect of the invention will now be described.
Since synthetic resins have interesting features such as a high productivity, being capable of widely selecting in designing, having a low weight, a high rust resistance and a high impact resistance. Therefore, they are widely used as materials such as construction materials, materials for electric parts and car parts.
Above all, since the polyolefin-type resin is inexpensive and moreover has excellent moldability, chemical resistance, thermal resistance and water resistance, and further has suitable electrical features, it is widely used as industrial materials and is one of the materials whose demand is expected to grow in the future.
However, the coating or painting and the adhesion of the polyolefin-type resins on a surface are difficult because of their non-polarity and their crystallinity. The polyolefin-type resins are different from the polyurethane-type resins, the polyamide-type resins, the acrylic resins and the polyester-type resins or the like which are polar resins. For these reasons, the polyolefin surface of molded articles is activated by a plasma treatment or a gas flame treatment to improve their adhesive properties. However, these processes are complicated and involve high equipment costs and large time losses. Further, depending on the complexity of the shape of the molded articles and the influence of the pigments and the additives in the resin, there scatters an effect by the surface treatment.
As a coating method without previous treatment, the use of a primer composition has been indicated for coating polypropylene car bumpers. However, this method includes complexity of "double-coat finishing". On the other hand, as a coating composition for a single-coat finishing, chlorinated polyolefins and cyclized rubbers or the like are used which have a high adhesion onto polyolefin-type resins. However, their weatherability, moisture resistance and gasoline resistance are low and they do not show properties to form a coated layer. For these reasons, an attempt to use a mixture of alkyd resins and acrylic resins which have excellent physical properties as coatings has been tested but, since the compatibility of the chlorinated polyolefins with the acrylic resins and the alkyd resins is inherently poor, the gloss of the coated layer is lowered and the outer appearance thereof is extremely damaged.
Several methods to improve this drawback have been disclosed. JP-A-58071966 discloses a coating composition obtained by copolymerizing an acrylic monomer with a chlorinated polyolefin. JP-A-59027968 discloses a coating composition essentially containing an isocyanate compound and a chlorinated polyolefin-modified copolymer having hydroxyl groups obtained by copolymerizing an acrylic monomer or the like having hydroxyl group with a chlorinated polyolefin. JP-A-62095372 discloses an adhesive resin composition containing as a main component an isocyanate compound and an acrylic-modified chlorinated polyolefin having hydroxyl groups obtained by copolymerization of an acrylic monomer or the like having hydroxyl group with a chlorinated polyolefin in presence of liquid-state rubber.
However, these compositions also form rigid films by painting and have low impact resistance and bending resistance.
Therefore, it may hardly be said that they form balanced coated layers.
On the other hand, several kinds of plastic films have been developed and used as materials for wrapping food. The materials for wrapping food are diversified in wrapping shapes and particularly, composite films obtained from a laminated film are widely used for protecting the object which is wrapped therein.
Generally, the ink for laminates which are used for wrapping is used and classified into two categories depending on the type of the film, at present. The first category is an ink composition used exclusively for polypropylene film which contains a chlorinated polypropylene and a chlorinated ethylene-vinyl acetate copolymer, as a main binder. The second category is used exclusively for polyester and nylon films and it is an ink composition comprising a urethane-type resin, as a main binder.
The former first category which is an ink composition containing chlorinated polypropylene and a chlorinated ethylene-vinyl-acetate copolymer, as a main binder, is explained, for example, in JP-B-86031670 and the ink composition obtained by chlorosulphonation of a copolymer of chlorinated ethylene and vinyl acetate is disclosed in JP-A-55145775. These compositions provide inks having a good adhesion onto non-treated polypropylene film and further show a good adhesion even in the case of laminate printing with the extrusion-laminating method.
However, they have a poor adhesion onto polyester and nylon films and are not suitable as printing ink used for laminates of these films.
The latter category which is an ink composition comprising a urethane-type resin, as a main binder, shows, as explained in JP-A-62153366 and JP-A-62153367 a good adhesion for the polyester and nylon films or other films having a polarity but does not show any adhesion with untreated polypropylene films and, therefore, is impossible for printing under a polypropylene-extrusion laminating method.
JP-A-64085226 disclosed, as a resin used as ink suitable for printing by the extrusion-laminating method applied to a polypropylene and for printing a laminate such as polyester and nylon films, a polyurethane-modified chlorinated polypropylene obtained by reacting a polyurethane comprising a free isocyanate group with a chlorinated polypropylene which has been modified with a vinyl monomer having hydroxyl group to introduce hydroxyl group into the above-mentioned chlorinated polypropylene.
However, in this method, the content of the chlorinated polypropylene is limited in the corresponding composition and the extrusion laminate strength of the polypropylene is insufficient.
In the existing circumstances, developments regarding strong binder compositions, easy surface treatment for various synthetic resins having different features, coating and printing inks are therefore expected.
The second aspect of the invention will now be described hereinafter.
Since the polyolefin-type resins are inexpensive and have several excellent properties such as moldability, chemical resistance, thermal resistance, water resistance and the like, they are recently widely used as a decoration paper and, particularly as a wall-decoration paper used in construction or the like.
However, the polyolefin-type resins are non-polar and highly crystalline as explained in the first aspect of the present invention. Thus, they have a drawback that it is difficult to coat the surface of the molded articles such as films or sheets of polyolefin-type resins and to cover the surface of another article with a polyolefin film or sheet by using adhesives.
Therefore, in the prior art, as explained in the first aspect of the invention, there have been proposed counter-measures such as a plasma treatment or gas flame treatment of the surface of the molded articles, a "double-coat finishing" using various primer compositions as observed in the surface coating for the car bumpers or a "single-coat finishing" by using a composition of a cyclized rubber and a chlorinated polyolefin and a mixture of alkyd resins and acrylic resins having the desirable coating properties, weatherability, moisture resistance and petrol resistance. However none of these countermeasures has sufficiently solved these problems.
Recently, the air bag for ensuring drivers' security in cars has been widely employed. In case of a car accident with an impact, a sensor catches the impact, and a high temperature-high pressure gas is produced. The air bag is immediately inflated by this gas and protects the driver's face and head portions against a front shock. The air bag also protects the driver's head portion and internal organs against a lateral shock.
In these air bags, flatly-woven cloths having a strong mechanical strength are usually employed which comprise filament yarns of 400-1000 Deniers made of a synthetic resin such as a polyester, 6,6-nylon, 6-nylon or the like. The internal surface of this cloth or the external surface thereof or both internal and external surfaces are coated with a chloroprene rubber, chloro-sulphonated polyolefins, a silicone rubber or other synthetic rubbers or elastomers to improve the thermal resistance, the weatherability, the fire-proof properties and the air-tightness of the cloth. The air bag is made of the resulting composite cloth which is bag shaped and must be light and be able to be folded compactly.
In JP-A-02270654, an air bag folded in a compact manner is described which is made of a thin film of a silicone rubber formed on a woven cloth. However, despite the excellent thermal resistance and weatherability of the silicone rubber, it is difficult to laminate the cloth. Some mold may appear on the obtained film thereby involving life-span troubles and facilitating the occurrence of pin holes and other problems.
In JP-A-04097842, an air bag is disclosed which is made by laminating a polyolefin-type resin or other ionomer resin, an ethylene-vinyl acetate copolymer, an ethylene-propylene copolymer on a woven cloth. However, the adhesion between the woven cloth and the resins, the weatherability as well as the inflation of the air bag were not sufficient.
In JP-A-04143145, a polyurethane is disclosed which is obtained from an isocyanate and a copolymer of vinyl chloride containing polyols coated onto a woven cloth. There, however, were also some drawbacks when using these resins, since these resins contain vinyl chloride, a plasticizer has to be added and when the air bag is kept during a long-time in its housing position, the plasticizer leaks out and the base cloth itself then becomes sticky.
The purposes of the invention will now be explained hereinafter.
The purpose of the first aspect of the invention is to provide an adhesive composition and a printing ink composition having excellent printing and adhesive properties for films of various resins having different features.
The purpose of the second aspect of the present invention is to provide a coating composition and a coating using this coating composition having excellent coatability and adhesion, improved coatability and the adhesion on the surface of polyolefin-type molded articles thereby giving a coated layer which is specifically used on a decoration paper made of the same resin, provides a coated layer without any deterioration of the external appearance or gloss of the film.
The purpose of the third aspect of the invention is to provide a method of producing a simple laminated cloth, by virtue of an improved adhesion between woven cloths and a resin, without any adhesion between the woven cloths, the corresponding air bag made from this laminated cloth and the manufacturing method thereof.